X-ray diffraction apparatus



July 12, 1949. Q G, KQPplUS' 2,476,156

X-RAY DIFFRACT I ON APPARATUS Filed Feb. 12,'1947 l i D//frclc fed /3 I Seam f POW f/Vi/f/va y5w/Wyk l OTTo-G, KOPPIU AGENT Patented July 12, 1949 UNITED *STATES riATENT `IFFflf'l?.

X-RAY DIFFRACTION APPARATUS .Otto G. Koppus, White Plains, N. Y.,=assignor to Philips Laboratories, Inc., Irvingtonon Hudson,

.Application February 12, 1947, Serial .Noz-128,031

13 Claims.

, 1 My invention relates. to. an Xeray apparatus and more particularly to an `X-ray apparatus for and a method of analyzingthe structure of ma terials under dynamic stress.

. X-radiation has been used to detect the hid-h.

den flaws in castings, metal objects, and to determine the orientation of crystals. However, it

hasbeen generally necessary to examine the specimen in its static state. The beam of X-rada tion is caused to impingeupon the object, e. am

a quartz crystal plate, and is then reiiected from one or more of the atomic planes constituting the crystal lattice of the material. Since the lattice structure remains constant while the object is in a static condition, the reflected beam of X-radiaff;

tion when suitably detected will reveal the spacings between atomic planes of the specimen being analyzed. These atomic reflecting planes appear as lines on a photographicfllm or other suitable recording medium; and the distances between? X-ray analysis.

While such methods have yielded'much valuable information concerning the-internal structure of the specimen in general, they do not give a reliable indication of conditions in the specimen under dynamic stress. Thus, they do not permit the study of such familiar phenomena as the creeping of Imetal under heat, thedistortion present in a Vibrating quartz crystal plate, a shaft subjected to recurring torsional stresses, or veven a i simple member subjected toV recurring tensionaly and compressional stresses.

It is an object of `my invention to provide a new and novel method for analyzing the internal strains and stresses of vmaterials which are 'subjected to dynamic strains and stresses.

" It is a further object of `my invention to provide a new and novel apparatus for detecting the l internal strains occurring within a structure of a moving member and observing the internal behavior of materials under dynamic stress.

These and further objects of my invention will appear as the specification progresses.

In accordance with .theinventiom I have found l that'by employing "ai s1-flitablyinodulatedY beam of X-radiation' whereinwthef: beam modulation cor-VV J' 2 responds to the periodicity ot the. stress when` the specimen is dynamically. strained, it isiwpossible to analyze eectively :the:nati-1rev of I dynamic stresses occurring .within .the specimen. When the specimen is` 'dynamically'stressed e.; subject to cyclically:recurringfstressesy-theatomic planes' constituting" thelattice structure, ofrthe material are in a state of motioni. Consequently,

' the spectrumlines shift imposition .with thev movement of the atomicfplanes within the specimen.

Preferably the beam ofv yK-radiation isfmodulated by a pulsingcircu-it arrangement and at a frequency which is :related to theY period of vibration of an oscillating specimen,-i. e.,a quartz-crystal plate, whereby thefmoVementof (the yplanes can be made tofcoincideifwithffthepulses ofv X- radiation and the-stresses present Withinithe material can be'effectivelystudied.; Furthermore by varying the `phase relation between the modulated beam of X-.rad-iatiom and;.the-oscil1ating specimen the ,stresses-.existing throughout the distortion range ofythespecimenamay be vreadily analyzed.

In order that the inventionl willfbewreadilyunderstood and.; carried.` into' eect itz will nowr be described in reference tothe accompanying drawing in which like'numerals refer to like partsand in which:

Fig. Al il-lustratesithe principle offthe invention applied to a simple yibratingfcrystal plate.

-. Fig. 2 illustrates". another embodiment ofthe ini, vention applied to anvibratingcrystal plate.

Fig. 3 illustrates one embodiment of the infvention for studying a sample oftmaterial which is dynamicallystressed.

' Referring nowfmorefparticularly to the fdrawing, in Fig. 1, agpiezo-.electriccrystal l0 which is subjected. to .X-ray ,analysis, is-mountedy between electrodes lle-ll Iand isfsubjected to dynamic stress by -couplingfithe `same to-an .oscillator lzphaving afrequency-equale to or harmonically vrelated to the-resonant frequency ofthe crystal.-

Forconveniencefthe crystal can; be selected from-the X-.put-Variety.. Wa-.ves of compression and rarefaction twill ,spread :through the crystal .causing theflattice. structure to befalterl nately compressedfand stretchedfout ofroriginal shape.- -A-s asource of X-radiationfthere is proyvided aniX-rayftubelfhaving ananode i4 and awcathode'- l5, and an :energizing power supply It, anode i4 being connected tor-:thehigh tension terminal ofpowersupply i6 thrugh apulse generating circuit llzoperated. inwsynchronism-with the oscillator.A I2. vfThecpulsegenerating circuit .conforms to those .well-known inf/the art and a detailed description thereof is not deemed necessary for the proper understanding of the invention; however, it may be in the form of a synchronously operated switch. A beam of X-radiation, generated by the tube I3 is reduced to a narrow pencil of X-radiation 30 by collimating slits I8 and impinges upon the activated crystal Ill. Within the crystal Ill the said beam is reilected by one of the atomic planes constituting the lattice structure of the crystal element .and upon emerging therefrom, the reflected beam is caused to enter an ionization chamber 2l. The resulting ionization current in the tube 2| has a pulsating component because of the pulsating nature of the impinging X-radiation, which is applied by electrodes "2--22 to a conventional amplifier 23, and impressed on an X-ray recorder 24 of any of the types well-known in the art. In accordance with the preferred arrangement according to the invention, the X-ray beam is modulated at a frequency which is proportional to the cyclical rate of vibration of the crystal whereby the periodic strains occurring withintthe specimen can thus be readily observed.

In Fig. 2, I have shown another embodiment of my invention wherein X-ray tube I3' having an anode I4' and a cathode I5 is provided with a control electrode I9 in the form of a grid or wire mesh. Control electrode I9 is energized from oscillator I 2 which energizes the sample tobe studied. By connecting the control electrode I9 to the oscillator I2' through phase shifting network 28, a phase displacement of the voltage applied to the control grid relative to the voltage applied to the sample may be obtained, whereby the relative phase between the modulated beam of X-radiation and the oscillating crystal may be Varied. Under these conditions it is thereby possible to analyze shifting strains within the lattice structure of the specimen.

In Fig. 3, there is shown an embodiment of my invention for analyzing the interior behavior of a crystalline material which does not possess piezo-electric properties. In this particular embodiment the specimen is mounted on piezo-electric crystal which is mounted in a set of electrodes and excited by a potential which is applied from the oscillator. While this is a particular example of mounting a specimen for analysis, the invention is equally applicable to any specimen which possesses crystalline properties and which is subjected to recurrent stresses and strains.

From the foregoing it will be seen that I have provided a simple and highly sensitive method of and apparatus for determining and analyzing dynamic stress in a crystalline material. More particularly, because the impinging X-radiation is of a recurrent cyclic nature, the reflected beam is readily amplified by conventional ampliers of high gains, thereby obviating the need of complex highly sensitive X-ray detection apparatus. Furthermore, since the X-radiation is pulsed, any point in the cyclic distortion of the sample can be studied by phase shifting adjustment.

While I have thus described my invention with specic examples and applications it will be obvious to those skilled in the art that various modifications therefore can be made without departing from the spirit and scope of my invention.

`What I claim is:

l. The method of studying the internal behavior of crystalline materials subject to changing internal stresses comprising the steps of. cyc1ica1ly modulating a beam p1' '2i-radiation at a 4 frequency harmonically related to the rate of change of stress within said crystalline material, directing the modulated beam of X-radiation at the material, and analyzing the beam after said beam emerges from the material.

2. The method of studying the internal behaviour of crystalline materials under dynamic stress comprising the steps of, straining the crystalline material to produce cyclically recurring stresses within the material, cyclically modulating a beam of X-radiation at a rate harmonically related to the change in stress within said material, directing said modulated beam of X-radiation at said stressed material, and analyzing the beam of X-radiation after said beam emerges from the stressed material.

3. The methodof studying the internal behaviour of crystalline materials under dynamic stress comprising the steps of, straining the material to produce cyclically recurring stresses within the material, modulating a beam 'of .X-radiation at a frequency which is harmonically -related to the cyclical recurrence of thestresses within the material, directing said modulated beam of X-radiation at said stressed material, analyzing the beam of X-radiation...after said beam emerges from the stressed material.

4. The method of studying the internalbehaviour of crystalline materials underdynamic stress comprising the steps of, straining the material to produce cyclically recurring stresses within the material, cyclically modulating a beam of -fri-radiation at a frequency which is harmonically related to the cyclical recurrence of stresses within the material, directing said cyclically modulated beam of X-radiation'at saidv material in controlled phase displacement with respect to said cyclicallyy recurring stresses, and analyzing the beam of X-radiation after said beam emerges from said stressed material.

5. The method of studying the internalbehaviour of crystalline materials under dynamic stress comprising the steps of, mounting a specimen of material on a piezoelectric crystal, applying a cyclically recurrent potential to said crystal. applying said cyclically recurrent potential to a control electrode of an X-ray generator in controlled phase displacement with respect to said potential applied to the crystal, generating a beam of X-radiation modulated by said cyclically recurrent potential applied to said electrode, directing said modulated beam of X-radiation at said specimen, and analyzing said beam of X- radiation after said beam emerges from said specimen.

6. A device for studying the internal behaviour of crystalline materials under cyclically recurring stresses comprising an X-ray generator, means to produce an X-ray beam modulated at frequency which is harmonically related to the frequency of said recurring stresses, means to impress said modulated beam on the crystalline material, and means for analyzing said beam after the beam emerges from said crystalline material.

7. A device for studying the internal behaviour of crystalliney materials under cyclically recurring stresses comprising anfX-ray generator, means to cyclically energize said X-ray generator to produce an X-ray beam modulated at a frequency which is harmonically related to the frequency of said recurring stresses, means to impress said modulated beam on the crystalline material, and means for analyzing said beam after the beam emerges from said crystalline material.

8. A device for studying the internal behaviour of crystalline materials subject to varying internal stresses comprising an X-ray generator having a control element, means to energize said X-ray generator, means to apply a cyclically recurrent potential having a frequency which is harmonically related to the cyclical recurrence of the strains in said material to Said control element for modulating a beam of X-radiation, a collimator for directing a Well-defined beam of X-radiation at the material, and means for analyzing the beam of X-radiation after said beam emerges from the material.

9. A device for studying the internal behaviour of crystalline materials under dynamic stress comprising means to produce cyclically recurrent stresses in said material, an X-ray generator having a control element for generating a modulated beam of X-radiation, means for energizing said X-ray generator, means for applying a cyclically recurrent potential having a frequency Which is harmonically related to the cyclical recurrence of the strains in said material to said control element for producing a modulated beam of X-radiation, a collimator for directing a Welldeilned beam of X-radiation at said material, and means for analyzing the beam of X-radiation after the beam emerges from the material.

10. A device for studying the internal behaviour of crystalline materials under dynamic stress comprising means to produce cyclically recurrent stresses in the material, an X-ray tube having anode and cathode electrodes, means to energize said electrodes, pulse generating means for applying a cyclically recurring potential having a frequency which is harmonically related to the cyclical recurrence of the strains in said material to said anode electrode for producing a pulsed beam of X-radiation, a collimator for directing a Well defined beam of X-radiation at the material, and means for analyzing the beam of X-radiation after said beam emerges from the material.

1l. A device for studying the internal behaviour of crystalline materials under dynamic stress comprising means to produce cyclically recurring stresses in said material, an X-ray tube for generating a beam of X-radiation having a control electrode, means to energize said X-ray tube, means for applying a cyclically recurring potential having a frequency which is harmonically related to the cyclical recurrence of the strains 6 in said material to said control electrode for modulating the beam of X-radiation generated by said tube, a collimator for directing a Well-dened beam of X-radiation at the material, and means for analyzing the beam of X-radiation after said beam of X-radiation emerges from the material.

12. A device for studying the internal behaviour of crystalline materials under dynamic stress comprising means to produce cyclically recurring stresses in said material, an X-ray tube having a control electrode for generating a beam of X-radiation, means to energize said X-ray tube, means to apply a cyclically recurring potential having a frequency which is harmonically related to the cyclical recurrence of strains in said material to said control electrode, a phase displacement element for controlling the relative phase displacement between said cyclically recurring potential and said recurring stresses in the material, a collimator for directing a well-defined beam of X-radiation at the material, and means for analyzing the beam of X-radiation after said beam emerges from the material.

13. A device for studying the internal behaviour of crystalline materials under dynamic stress comprising a piezo-electric crystal element for imparting a cyclically recurrent strain to said material, an X-ray generator having a control element, means for energizing said X-ray generator, means for applying a cyclically recurrent potential having a frequency which is harmonically related to the cyclical recurrence of strains in said material to said control element for generating a modulated beam of X-radiation and to said crystal, a phase displacement element for controlling the relative phase displacement between the potentials applied to said control element and said crystal, a collimator for directing a Well defined beam of X-radiation at the material, and means for analyzing the beam of X-I'adiation after said beam emerges from the material.

OTTO G. KOPPIUS.

REFERENCES CITED The following referenlces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,377,862 Bond June 12, 1945 2,386,785 Friedman Oct. 16, 1945 

